REFACTOR: Rename many "Unnamed" parse tree nodes.

In Irony, if you write:

     A.Rule = B + (C | D)

it will automatically generate a term with a name like `Unnamed9` for
the `C | D` part. These are opaque when analyzing the grammar in
Irony.GrammarExplorer. To make that task easier, I am introducing some
named terms to replace them. There are now only 3 unnamed terms.
Pass multiple parameters to a method invocation.

I modified the parser to remove support for chained range operators
(`1..2..3`), to allow this to parse correctly. I don't think that's
important, and I don't know how to fix the parser correctly.